Two Cases of Myeloid Sarcoma at Rare Sites: Cytological Manifestations and Diagnostic Experience.

Myeloid sarcoma is a rare extramedullary manifestation of acute myeloid leukemia, and primary involvement of the gastrointestinal tract and uterine cervix is particularly uncommon. Due to its low incidence and nonspecific clinical manifestations, the rates of clinical misdiagnosis and missed diagnosis remain high. Herein, we report two cases of myeloid sarcoma arising at rare sites. Case 1 was a 52-year-old male who presented with acute gastrointestinal obstruction. Intraoperative frozen section favored lymphoma, whereas touch imprint cytology of the tumor cut surface revealed numerous round to oval blasts with scant basophilic cytoplasm, finely granular nuclear chromatin, and small nucleoli, consistent with myeloid blast morphology and suggestive of myeloid sarcoma. Postoperative paraffin pathology confirmed the diagnosis of small intestinal myeloid sarcoma. Case 2 was a 63-year-old postmenopausal female who presented with unexplained vaginal discharge. Cervical liquid-based cytology demonstrated scattered medium-sized cells with finely dispersed nuclear chromatin and small nucleoli. Subsequent immunocytochemistry showed MPO and CD117 positivity, identifying myeloid blasts prior to tissue biopsy. Both cervical biopsy and bone marrow examination confirmed the diagnosis of cervical myeloid sarcoma. Cytological evaluation provided valuable morphological clues at different clinical stages, guided subsequent immunohistochemical workup, and shortened the diagnostic timeline in both cases. These cases demonstrate the cytomorphological features of MS at rare sites, and improving awareness of cytological manifestations of MS at atypical sites is helpful for early diagnosis and timely clinical intervention.